Question

Ten one-rupee coins are put on top of each other on a table. Each coin has a mass $m$. The reaction of the $6^{th}$ coin (counted from the bottom) on the $7^{th}$ coin is

• A. $4mg$
• B. $6mg$
• C. $7mg$
• D. $3mg$

Answer 1

Answer: (A)

The sixth coin is under the weight of four coins above it. Hence,
Reaction of the $6^{th}$ coin on the $7^{th}$ coin
= Force on the $6^{th}$ coin due to $7^{th}$ coin = $4mg$